001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017
018package org.apache.commons.jxpath.ri.compiler;
019
020import org.apache.commons.jxpath.ri.EvalContext;
021import org.apache.commons.jxpath.ri.QName;
022
023/**
024 * An element of the compile tree holding a variable reference.
025 */
026public class VariableReference extends Expression {
027
028    private final QName varName;
029
030    /**
031     * Constructs a new VariableReference.
032     *
033     * @param varName variable name
034     */
035    public VariableReference(final QName varName) {
036        this.varName = varName;
037    }
038
039    @Override
040    public Object compute(final EvalContext context) {
041        return computeValue(context);
042    }
043
044    @Override
045    public boolean computeContextDependent() {
046        return false;
047    }
048
049    /**
050     * Returns the value of the variable.
051     *
052     * @param context EvalContext against which to compute the variable's value.
053     * @return Object
054     */
055    @Override
056    public Object computeValue(final EvalContext context) {
057        return context.getRootContext().getVariableContext(varName);
058    }
059
060    /**
061     * Gets the variable name.
062     *
063     * @return QName
064     */
065    public QName getVariableName() {
066        return varName;
067    }
068
069    @Override
070    public boolean isContextDependent() {
071        return false;
072    }
073
074    @Override
075    public String toString() {
076        return "$" + varName;
077    }
078}